John Fogerty (CCR), although CCR's performance was not released on the film nor the soundtrack. Rumor has it the record company owning their rights couldn't come to an agreement. No surprise there, given all of the legal issues CCR and Fogerty had over the decades with them.
Fogerty is a raging liberal these days, so he would fit right in. Which saddens me because CCR was one of my all-time favorite groups.